Cognitive closure refers to the idea that the human mind is "closed" to some facts--that there are things human beings are simply not able to know, not because there is not enough time to figure them out, but because the human mind does not have the capacity to comprehend them. A weak version of cognitive closure suggests that some aspects of the universe are simply more difficult for humans to understand than other aspects. If so, all facts can be comprehended once we discover the correct conceptual frameworks. Cognitive closure may account for the slow development of some protosciences.